This invention relates to ceramic ware, and more specifically to the firing of the same.
It is conventional practice with certain types of kilns to load the ware onto cars which are progressed through the kiln to effect the firing, and it is necessary to support the ware on the cars to avoid damage to the ware which is particularly vulnerable whilst in the unfired condition.
The ceramic articles are usually supported on appropriately shaped shelves known in the art as batts, and the batts are spaced one above the other with props between them arranged in vertically aligned series. The lowermost batts are spaced above the base of the car by special props known as mid-feathers. All of the batts and props are made of refractory materials, and the base of the car is also provided with a refractory structure.
In the interests of stability it is accepted practice to bed the bottom tier of batts onto the top of the mid-feathers with cement or fireclay, although they can be placed dry. The other tiers of batts above the base tier are supported by cylindrical refractory props (usually tubular); these are normally mated dry to a recessed or embossed cap or disc below and above each prop. These caps or discs can be cemented to the props, but batts are usually dry placed to facilitate ease of replacement.
In use the loaded car is moved at least into and out of the kiln and possibly also progressed through the kiln, and may be subject to physical shock, for example from one car bumping into another, or other shock transmitted through the car wheels. It is also subject to thermal shock, and the complete structure undergoes differential expansion and contraction. Consequently the batts often crack and break and although this may not initially lead to collapse of the structure, it is considered necessary to effect repairs, for example inserting additional props or replacing cracked batts, because of the fear that the structure may collapse and not only damage the load of ware, but jam the kiln so as possibly to necessitate the kiln being shut down whilst the car is removed. As a result, the costs of maintaining the cars and their structure is high, and it is the object of the present invention to provide improvements which will reduce this cost.